- Test small; profile low domal.
- Apical disc large, dicyclic. Forming a raised knob in females (brood-protecting, the juveniles carried around the elevated apical disc in females).
- Ambulacral plating trigeminate, compound in echinid style. Pore-pairs small, arranged uniserially, forming slight arcs only close to the peristome. One primary tubercle to each compound plate close to the pore zone, plus one smaller perradial tubercle.
- Interambulacral plates with central primary tubercle and few smaller secondary tubercles. No obvious sculpturing or sutural pits, except in females, where the uppermost interambulacral plates bear a radiating sculpture around the secondary tubercles.
- Primary tubercles imperforate and distinctly crenulate.
- Peristome large without obvious buccal notches.
- Perignatic girdle with small, unfused auricles.
- Spines thorny, without cortex, about half of test diameter in length.
- Globiferous pedicellariae with open blade and 2-3 lateral teeth to each side and single venom glands.
||Recent; North Atlantic (around Iceland).
||Hypsiechinus coronatus Mortensen, 1903, by monotypy.
||Only the type.
|Classification and/or Status
||Differs from Trigonocidaris by its thorny spines, largely unsculptured corona and its distinct sexual dimorphism. Note that Mortensen placed this genus in the Trigonocidaridae.
Mortensen, T. 1943. A Monograph of the Echinoidea. III, 2. Camarodonta. I. Orthopsidae, Glyphocyphidae, Temnopleuridae and Toxopneustidae. C. A. Reitzel, Copenhagen, vii+553 pp.